Understanding mathematical and mathematical concepts is one of my fundamental abilities.
Therefore, it is necessary to teach mathematics by emphasizing concept understanding so that students
are trained to solve problems with the concepts they understand appropriately. This study aims to analyze
the knowledge of mathematical concepts of students at junior high school level grade VIII on linear
function material. This research is qualitative research with a descriptive method. The research subjects
were VIII grade students, as many as 33 students. Data collection through two description questions was
then analyzed according to the ability of high, medium, and low student categories. Furthermore, direct
interviews were conducted to obtain more in-depth information about students' understanding of
mathematical concepts. The results showed that 39.39% of students had high-category mathematical
concept understanding ability (ST), 6.06% of students in the medium category (SS), and 54.55% of students
in the low category (SR). ST fulfills all indicators with the correct answer, and SS fulfills all indicators, but
the answers produced could be more precise. SR cannot apply concepts, so it only fulfills some indicators,
which results in errors in solving problems.
Keywords: Concept Understanding, Linear Functions.